Adding in ability to check status of automatic branch jobs in jenkins

The current documentation for integrating Jenkins and Gitlab EE indicates that the Gitlab Hook Plugin should be used. When you use that plugin you can set up Jenkins to automatically create new jobs for the branches used in merge requests. The CI Status check for Jenkins does not currently handle those automatic jobs. The result of this is shows an error checking the status on all Merge Requests. This merge request is a small change to the jenkins_service to utilize the ref param being passed in and appending the branch name if not master to the project url which will allow the status checks to succeed.